Unlocking is harder than it should be - password doesn't have focus

I'm finding it quite frustrating to unlock my M10 when I come back to it after a few minutes away.

To reproduce:-

* Attach a bluetooth keyboard to a bq M10 running rc-proposed (I'm using a logitech k480)
* Allow the M10 (and keyboard) to go to sleep - so wait 10 mins or so

Now, either:-

* Press a key on the keyboard - e.g. shift
* Display wakes up, but focus is not on the password field.

Or

* Tap power button on M10 to wake it (but not the keyboard)
* Display wakes up, but focus is not on password field
* Tap on password field to give it focus
* OSK appears
* Start typing on the keyboard (not OSK) your password (because it's easier)
* Keyboard wakes up
* OSK disappears
* Focus is again lost from password field

All in all, quite frustrating to unlock a device which powers down after a short period (battery save!).

Expected behaviour:-

* On keyboard wake, password field should be focussed
* Focus should not be lost when switching OSK/physical keyboard

Possible adverse side effect to above expectation:-

Probably having focus on that field may mean accidental unlock attempts in pocket/bag.